Understanding Craniectomy Surgery

This lifesaving procedure relieves pressure and bleeding in the brain.

A craniectomy is a type of surgery that is sometimes necessary to relieve a buildup of pressure in the skull (intracranial pressure) caused by a traumatic brain injury. In a craniectomy, a portion of the skull is removed, allowing the brain to decompress.

Here's what to know about how and when a craniectomy is performed, the potential risks and complications, and how it differs from similar types of procedures.

The Difference Between Craniotomy and Craniectomy
Verywell / Gary Ferster

What Is a Craniectomy?

In a craniectomy, a neurosurgeon cuts through the scalp, folds back the skin, and then uses a surgical drill to remove a section of the skull, called a bone flap, in order to relieve pressure and swelling in the brain. The bone flap is typically round or oval.

A craniectomy is performed under general anesthesia. Prior to the surgery itself, the appropriate section of your scalp will be shaved and cleaned with an antiseptic.

Purpose of Procedure

A craniectomy is an emergency procedure used to relieve swelling in the brain due to an acute traumatic brain injury or a hemorrhagic stroke. If the brain swells, blood builds up and pushes against the skull, with nowhere to go. A craniectomy prevents the brain from compressing, a situation that can be fatal.

Potential Risks

Risks and complications that can occur after a craniectomy include:

  • Postoperative infection
  • Wound healing complications
  • Intracerebral hemorrhage
  • Extracranial cerebral herniation (when brain tissue emerges outside the opened area of the scalp)
  • Leakage of cerebrospinal fluid
  • Fistulae
  • Seizures and epilepsy

Complications that can occur long after the surgery include:

  • Subdural hygroma (buildup of cerebrospinal fluid in the brain)
  • Hydrocephalus
  • Syndrome of the Trephined (a constellation of symptoms including motor weakness, cognitive deficits, headache, and seizures)

Craniectomy Recovery Time

It can take several weeks for your surgical site to heal after a craniectomy. During this time, you may need to wear a special helmet to protect your head and facilitate healing. You will be given pain medications; a nurse or other healthcare worker will tend to your surgical wound so it doesn't become infected.

Eventually, you will undergo a follow-up surgery to replace the bone flap that was removed.

However, because a craniectomy is done in emergency situations involving very serious swelling of the brain, there is no typical length of a hospital stay or recovery time. Even after the surgical site heals, it is possible to require months and even years of rehabilitation if your brain has been severely damaged.

A brain injury can result in the loss of some physical and/or cognitive abilities. Depending on a patient's specific needs, they may require physical therapy, occupational therapy, cognitive therapy, and speech therapy.

Similar Procedures

Other procedures that involve penetrating the skull include:


In a craniotomy, a piece of the skull is also removed. However, the purpose of a craniotomy is typically to allow a surgeon access to the brain in order to remove a brain tumor, as opposed to relieving swelling in the brain.

A craniotomy can be performed under general anesthesia. In some cases, however, a patient may only be lightly sedated with the surgical area numbed; this is called an awake craniotomy. Awake craniotomies are typically performed when the lesions are in areas of the brain that control speech and motor function.

Craniotomies can also be used to clip an aneurysm. A brain aneurysm is a bulging area in a weakened brain artery that is at risk of rupturing, potentially causing a hemorrhagic stroke or death. To prevent this possibility, a surgeon places a metal clip across the "neck" of the aneurysm to prevent rupture.

Burr Hole Surgery

Unlike with a craniotomy and craniectomy, a burr hole procedure does not involve removal of a bone flap. Instead, the surgeon makes one or more small holes in the skull with a surgical drill. Burr hole surgery is performed under general anesthesia.

The primary reason for burr hole surgery is to treat a subdural hematoma. Subdural hematomas can be acute, in the case of a mild brain injury due to a fall or a sports injury. Chronic hematomas are more common in older people who take anticoagulant medications, or in those who drink alcohol heavily. Both types can lead to a buildup of pressure in the brain, warranting burr hole surgery to relieve it.

The Bone Flap 

One of the key differences between a craniectomy and a craniotomy is what happens to the bone flap after the necessary surgery is performed.

In a craniotomy, the bone flap is usually reattached with plates, sutures, or wires, allowing it to heal and mend like any other broken bone. After several months the bone is nearly as strong as it was prior to surgery.

A craniectomy also includes the removal of a bone flap, but in this case, it is not returned to its location after the procedure is finished. This may be due to trauma to the bone itself, because the brain is too swollen to permit the reattachment of the bone flap, or because the surgeon feels it is in the patient’s best interest. If there is an infection in the area, for example, the bone flap may be discarded.

If a bone flap is removed, but not able to be returned during the procedure, it can still be put back into place at a later time. In this situation, the surgeon will place the bone flap in another location. In most cases, the surgeon will make an incision in the abdomen, large enough to slip the piece of bone inside like an envelope under the fatty tissue of the belly. There it is protected and preserved by the patient’s own body. Bone flaps can also be placed in a special deep freezer in the hospital lab for storage until it can be replaced.

If the bone flap cannot be returned, prosthetics and artificial bone are also available to aid the reconstruction at a later date. Replacing the missing piece is important because the brain is minimally protected without the bone in place. Like the "soft spot" on a newborn's head, the lack of bone could make it possible for a penetrating brain injury to occur. 

Frequently Asked Questions 

Why does a bone flap need to be placed in the stomach after a craniectomy?

A bone flap may need to be reattached to the skull at a later date after a craniectomy. This may be necessary to allow the swelling in the brain to subside. In this case, it is common for the surgeon to make an incision in the patient's abdomen and "store" the piece of bone under the fatty tissue of the belly in order to preserve it until it can be reattached.

Does the surgeon reattach the bone flap?

In a craniotomy, the surgeon replaces the bone flap right after the brain surgery, using sutures, plates and wires. That portion of the skull will then heal and mend just like any other bone.

How does craniotomy surgery differ from a craniectomy?

A craniectomy is an emergency procedure used to relieve swelling in the brain due to a stroke or a traumatic brain injury. A craniotomy is done in order to allow a surgeon to remove a brain tumor, In both cases, a bone flap, or section of the skull, is removed. With a craniotomy, this bone flap is replaced right away, while in a craniectomy the flap is often preserved and put back at a later time,

A Word From Verywell 

Brain surgery is a very serious procedure under any circumstances, but a craniectomy is done when there is an immediate risk to the brain and neurological function due to severe brain injury or stroke. If you or a loved one has sustained brain damage, you will be referred to a specialized rehabilitation facility where you can work on regaining as much physical and cognitive function as possible. There are also numerous organizations geared to supporting those with brain inuries, including the Brain Injury Association of America.


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11 Sources
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  1. Sahuquillo J, Dennis JA. Decompressive craniectomy for the treatment of high intracranial pressure in closed traumatic brain injury. Cochrane Database of Systematic Reviews 2019, Issue 12. Art. No.: CD003983. doi:10.1002/14651858.CD003983.pub3

  2. University of Rochester. Craniectomy.

  3. Gopalakrishnan MS, Shanbhag NC, Shukla DP, Konar SK, Bhat DI, Devi BI. Complications of decompressive craniectomyFront Neurol. 2018;9:977. Published 2018 Nov 20. doi:10.3389/fneur.2018.00977

  4. Moffit Cancer Center. What is recovery like after a craniectomy?

  5. Ponsford J, Lee NK, Wong D, et al. Factors associated with response to adapted cognitive behavioral therapy for anxiety and depression following traumatic brain injury.J Head Trauma Rehabil. 2019 Jul 29. doi:10.1097/HTR.0000000000000510

  6. American Cancer Society. Surgery for adult brain and spinal cord tumors.

  7. Zhang K, Gelb AW. Awake craniotomy: indications, benefits, and techniques. Colombian Journal of Anesthesiology: April-June 2018 - Volume 46 - Issue 2S - p 46-51 doi:10.1097/CJ9.0000000000000045

  8. Johns Hopkins Medicine. Craniotomy.

  9. Johns Hopkins Medicine. Burr holes.

  10. Ernst G, Qeadan F, Carlson AP. Subcutaneous bone flap storage after emergency craniectomy: cost-effectiveness and rate of resorption. J Neurosurg. 2018 Dec 1;129(6):1604-1610. doi: 10.3171/2017.6.JNS17943

  11. Johns Hopkins Medicine. Cranioplasty.